This invention relates to mobile communication systems. More particularly, and not by way of limitation, the invention is directed to an apparatus and method for fine-grained access control in a mobile communication network.
In cellular communication networks such as GSM, small cells known as picocells may serve small areas such as parts of a building, a street corner, or an airplane cabin. A picocell is generally smaller than a microcell, which in turn, is smaller than a macrocell. Picocells are usually used to extend coverage to indoor areas where outdoor signals do not reach well, or to add network capacity in areas with very dense phone usage, such as train stations. The picocells are traditionally provided as coverage or capacity extensions and do not include an access control mechanism. This means that all users allowed to access the macrocells of a public land mobile network (PLMN) will also be allowed to access the microcells and picocells of that same PLMN.
In addition, the term “femtocell” is being introduced (to indicate that the coverage area is relatively small and in some cases even smaller than the coverage of picocells). These femtocells are normally meant for a limited subset of the subscribers allowed access to the macrocells of a PLMN. For example, a femtocell may cover only the geographical area of a house and the allowed users may be the members of the family living in that house. So clearly a new access control mechanism is needed to control access to the femtocells. If the existing core network (CN)-level access control is used for the access control mechanism for the femtocells, it would add a significant signaling load to the core network because the core network would be involved in all access control procedures.
In Wideband Code Division Multiple Access (WCDMA) cellular networks, there is currently no equivalent to femtocells with access control support. Current access control procedures are not fine-grained enough to support a large number of very small cells.
It would be advantageous to have an access control apparatus and method, which reduces the signaling load on the core network while providing access control sufficiently fine-grained to support a large number of very small cells. The present invention provides such an apparatus and method.